Cobalt is an important commodity used primarily in high-technology fields where materials require high strength; resistance to heat, corrosion, abrasion, and wear; or superior magnetic properties. A significant portion of cobalt consumption is for non-metallic products such as dryers in paints, and in pigments, enamels, rubbers, and catalysts.
Most cobalt production is in Southern Africa, primarily in Zaire and in Zambia. The U.S. is almost totally dependent on imports for cobalt, having no significant primary production. However, lead ore reserves in Missouri are estimated to contain 200 million pounds of cobalt. Most of this cobalt is present as the mineral siegenite (Ni, Co).sub.3 S.sub.4. Siegenite is a member of the linnaeite series of minerals, and sometimes contains some copper and iron. Missouri cobalt-bearing ores are often characterized as a complex interlocking of siegenite with chalcopyrite, sphalerite, and dolomite.
Flotation test work has indicated that cobalt minerals tend to be readily depressed by most metal sulfide depressants, and especially by cyanides. It has also been observed that the number of flotation cleaner stages appeared to adversely affect the recovery of siegenite into a cobalt concentrate. Because of these flotation properties, metallurgical test work usually focused on the depression of siegenite during flotation of other sulfide minerals, usually with cyanide chemicals, which tended to produce the most consistent results.